New research from Johns Hopkins University shows that the galaxies of the universe are getting hotter. The universe was created somewhere around 13 billion years ago and since that time planets, solar systems, and galaxies were formed out of the super-heated material that exploded forth from the big bang. It would be an easy assumption to think that since that time everything has just been cooling off and calming down, however, this new research shows that is just not the case. The universe may have been cooling off for the first 3 billion years but over the last 10 billion the galaxies of the universe have been heating up.
How do we know?
Researchers from Johns Hopkins University looked back at two decades worth of data from the Sloan Digital Sky Survey and the ESA’s Planck Mission to measure the temperature of galaxies in the universe. They discovered that the average temp of galaxy clusters today is about 4 million degrees Fahrenheit. Which is about 4 times hotter than the Sun’s corona. Furthermore, over the last 10 billion years the average temperature has increase by about 10 times. The gain in heat is the result of gases being pulled into the galaxies by gravity. Which sounds simple enough, but this drag is so powerful that the effect is similar to meteoroids hitting Earth’s atmosphere. As gravity pulls them downward they burn up and often disintegrate.
“We have measured temperatures throughout the history of the universe,” said Brice Menard, a Johns Hopkins professor of physics and astronomy. “As time has gone on, all those clusters of galaxies are getting hotter and hotter because their gravity pulls more and more gas toward them.”
In order to make this discover Yi-Kaun Chiang, a post-doctoral researcher at Johns Hopkins and Brice Menard, a Johns Hopkins professor of physics and astronomy had to develop a new technique. Using this technique, they were able to estimate the redshift of gas concentrations in microwave images. The “redshift” is the lengthening of light waves as they get older. To put it another way, the longer the wavelength the older the light wave. Using this information, they were about to collect data from these gas concentrations from up to 10 billion years ago. From that information they could see that over time the gases were becoming more concentrated and adding heat to the galaxies.
You can learn more about this discovery and their findings in the Astrophysical Journal.